Sialadenitis is an inflammation of a salivary gland that occurs due to a bacterial or viral infection or autoimmune causes. There are often associated obstructing salivary stones and Gland hyposecretion is often present. Symptoms are swelling, pain, erythema, and tenderness. Diagnosis is clinical. CT, ultrasound, or MRI may help identify the cause. Treatment is with antibiotics.
Sialadenitis is an inflammation or infection of the salivary glands that can be acute or chronic, with diverse etiologies, including bacterial, viral, allergic, obstructive, and autoimmune (1).
General reference
1. Kim MJ, Milliren A, Gerold DJ Jr. Salivary Gland Disorders: Rapid Evidence Review. Am Fam Physician. 2024;109(6):550-559.
Etiology of Sialadenitis
Sialadenitis usually occurs after hyposecretion or duct obstruction but may develop without an obvious cause. The major salivary glands are the parotid, submandibular, and sublingual glands.
Sialadenitis is most common in the parotid gland and typically occurs in:
Patients in their 50s and 60s
Chronically ill patients with xerostomia
Patients with Sjögren syndrome or IgG4-related disease
Adolescents and young adults with anorexia
Children (age 1 to18 years) with juvenile recurrent parotitis of undetermined etiology
The most common causative bacterium is Staphylococcus aureus, and most common causative virus is paramyxovirus (eg, mumps). Other bacteria include streptococci, coliforms, and various anaerobes.
Inflammation of the parotid gland can also develop in patients who have had radiation therapy to the oral cavity or radioactive iodine therapy for thyroid cancer (1, 2, 3). Although sometimes described as sialoadenitis, this inflammation is rarely a bacterial infection, particularly in the absence of fever. Allergy, infection, genetic inheritance, and autoimmune disorders have not been confirmed as causes. Juvenile recurrent parotitis is type of sialadenitis affecting the parotid gland. It is a disorder of unknown etiology affecting children (most commonly 4 to 6 years old) and often resolving by puberty. Except for possibly mumps, juvenile recurrent parotitis remains the second most common form of parotitis in children (4).
Etiology references
1. Erkul E, Gillespie MB. Sialendoscopy for non-stone disorders: the current evidence. Laryngoscope Investig Otolaryngol. 2016;1(5):140–145. doi: 10.1002/lio2.33
2. An YS, Yoon JK, Lee SJ, et al. Symptomatic late-onset sialadenitis after radioiodine therapy in thyroid cancer. Ann Nucl Med. 2013;27(4):386–391. doi: 10.1007/s12149-013-0697-5
3. Kim YM, Choi JS, Hong SB, et al. Salivary gland function after sialendoscopy for treatment of chronic radioiodine-induced sialadenitis. Head Neck. 2016;38 (1):51–58. doi: 10.1002/hed.23844
4. Schwarz Y, Bezdjian A, Daniel SJ. Sialendoscopy in treating pediatric salivary gland disorders: a systematic review. Eur Arch Otorhinolaryngol. 2018;275(2):347–356. doi: 10.1007/s00405-017-4830-2
Other Salivary Gland Infections
Mumps often causes parotid swelling (see table ).
Patients with HIV infection often have parotid enlargement secondary to one or more lymphoepithelial cysts.
Cat-scratch disease caused by Bartonella infection often invades periparotid lymph nodes and may infect the parotid glands by contiguous spread. Although cat-scratch disease is self-limited, antibiotic therapy is often provided, and incision and drainage are necessary if an abscess develops.
Atypical mycobacterial infections in the tonsils or teeth may spread contiguously to the major salivary glands. The purified protein derivative (PPD) test may be negative, and the diagnosis may require biopsy and tissue culture for acid-fast bacteria. Treatment recommendations are controversial. Options include surgical debridement with curettage, complete excision of the infected tissue, and use of antituberculosis medication therapy (rarely necessary).
Salivary glands may also be involved in sarcoidosis and IgG4-related disease. Sjögren syndrome may manifest as parotid or submandibular gland swelling
Symptoms and Signs of Sialadenitis
Fever, chills, and unilateral pain and swelling develop in patients with sialadenitis. The salivary gland is firm and diffusely tender, with erythema and edema of the overlying skin. Pus can often be expressed from the duct by compressing the affected gland and should be cultured. Focal enlargement may indicate an abscess.
Diagnosis of Sialadenitis
CT, ultrasound, or MRI
Other tests (serology, IgE, eosinophils, culture)
CT, ultrasound, and MRI can confirm sialadenitis or abscess that is not obvious clinically, although MRI may miss an obstructing stone. Ultrasound is considered first-line imaging and is the preferred test in children (1). It also has high specificity, sensitivity, and overall accuracy in identifying and differentiating between autoimmune etiologies (2). Diffusion weighted MRI can aid in differentiating sialadenitis from salivary gland tumors (3).
If pus can be expressed from the duct of the affected gland, it is sent for Gram stain and culture.
When sialadenitis is recurrent and involves multiple glands and an autoimmune etiology is suspected, adjunctive testing including antibody and eosinophil measurements or a surgical biopsy may be considered. Serum IgG4 levels may be elevated in IgG4-related sialadenitis. Autoantibodies (eg, anti-SSA [Ro] and anti-SSB [La]) may be elevated in Sjögren syndrome. Serum IgE and eosinophil counts may be elevated in allergy-related sialodochitis.
Diagnosis references
1. Kim MJ, Milliren A, Gerold DJ Jr. Salivary Gland Disorders: Rapid Evidence Review. Am Fam Physician. 2024;109(6):550-559.
2. Shimizu M, Okamura K, Kise Y, et al. Effectiveness of imaging modalities for screening IgG4-related dacryoadenitis and sialadenitis (Mikulicz's disease) and for differentiating it from Sjögren's syndrome (SS), with an emphasis on sonography. Arthritis Res Ther. 2015;17(1):223. Published 2015 Aug 23. doi:10.1186/s13075-015-0751-x
3. Araujo JP, Terra GTC, Cortes ARG, et al. A comparison of conventional and diffusion-weighted magnetic resonance imaging in the diagnosis of sialadenitis and pleomorphic adenoma. Oral Surg Oral Med Oral Pathol Oral Radiol. 2019;127(5):451-457. doi:10.1016/j.oooo.2018.10.006
Treatment of Sialadenitis
Antistaphylococcal antibiotics
Local measures (eg, sialagogues, warm compresses)
The treatment of sialadenitis is based on the underlying cause (1). Treatment for underlying autoimmune, allergic, and obstructive etiologies must be administered if these etiologies are confirmed. Viral infections are typically self limited and treated with supportive care. Initial treatment for bacterial sialadenitis is with antibiotics active against S. aureus (eg, dicloxacillin, 250 mg orally 4 times a day, a first-generation cephalosporin, or clindamycin), modified according to culture results. With the increasing prevalence of methicillin-resistant S. aureus (MRSA) especially among older adults living in extended-care nursing facilities, vancomycin is often required. Chlorhexidine 0.12% mouth rinses 3 times a day will reduce bacterial burden in the oral cavity and will promote oral hygiene.
Hydration, sialagogues (eg, lemon juice, hard candy, or some other substance that triggers saliva flow), warm compresses, gland massage, and good oral hygiene are also important. Abscesses require drainage.
When a stone or obstruction of the salivary ducts are considered, the patient may undergo sialendoscopy with glucocorticoid injection. Occasionally, a superficial parotidectomy, parotid duct ligation, or submandibular gland excision is indicated for patients with chronic or relapsing sialadenitis.
Treatment reference
1. Kim MJ, Milliren A, Gerold DJ Jr. Salivary Gland Disorders: Rapid Evidence Review. Am Fam Physician. 2024;109(6):550-559.
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